Distillation systems are for evaporating and separating mixed materials existing in a feedstock material based on difference of boiling point. In the upper portion of a distillation system, a material with a low boiling point (high volatile component) is evaporated in the form of overhead vapor, while in the lower portion of the distillation system, a material with a high boiling point (low volatile component) is separated in a non-distilled form. Here, the high volatile component and the low volatile component may each be a singular component, or a mixture of two or more components.
Such a distillation system essentially includes an evaporative separator configured to separate materials according to difference of boiling point. Examples of such an evaporative separator include distillation column, rectification column, stripping column, stripping vessel and stripper, etc.
In the case of extracting a high volatile component to be prepared as a subject product, the rectification column is used, but in the case of extracting a low volatile component to be prepared as a subject product, the stripping column or stripping vessel (or stripper) is used. Stripping columns are usually used to extract a low volatile component having a low viscosity, and stripping vessels (or strippers) are usually used to extract a low volatile component having a high viscosity.
FIG. 1 is a view schematically illustrating a conventional distillation system having a stripping vessel. Referring to FIG. 1, the conventional distillation system 10 having a stripping vessel consists of a the stripping vessel 110 where a feedstock material is separated into a low volatile component and a high volatile component, and a condenser 120 where overhead vapor of the high volatile component is condensed. The stripping vessel 110 strips and refines the high volatile component, and recovers the refined high volatile component as raw material, while drying the low volatile component having a high viscosity to obtain a final product.
When steam is supplied from a steam supplier 160 to the stripping vessel 110, the steam directly contacts the mixed material of a high viscosity in the lower portion of the stripping vessel 110 and transfers heat thereto. By this heat, the high volatile component of the mixed material is evaporated and is discharged as overhead vapor together with water vapor, and the high boiling point material of the mixed material is discharged externally together with condensate water of the steam.
However, the distillation system of FIG. 1 separates the feedstock material into a low volatile component and a high volatile component in a singular stripping vessel 110, and thus has a problem that the feedstock material cannot be separated with precision, thereby reducing the purity or recovery rate of product.
In order to solve the aforementioned problem of the distillation system illustrated in FIG. 1, a distillation system having two or more stripping vessels was proposed.
FIG. 2 is a view schematically illustrating a conventional distillation system provided with two or more stripping vessels. Referring to FIG. 2, the distillation system 20 having two stripping vessels includes a first stripping vessel 111 to which a feedstock material is supplied, a second stripping vessel 112 to which material not stripped in the first stripping vessel 111 is supplied, a condense-evaporator 120 where overhead vapor discharged from the first stripping vessel 111 and water exchange heat, a condenser 130 where overhead vapor not condensed in the condense-evaporator 120 is condensed for the last time, and two compression modules 141, 142.
In the distillation system 20 having the two stripping vessels, first of all, a feedstock material is supplied to the first stripping vessel 111. When steam is supplied from the steal supplier 160 according to the temperature required in the first stripping vessel 111, a high volatile component of the feedstock material is discharged as overhead vapor, while a low volatile component is separated in a non-distilled form in a lower portion of the first stripping vessel 111. Here, in the first stripping vessel 111, only the high volatile components having a boiling point below a certain temperature are discharged as overhead vapor, whereas the materials having a boiling point of or above the certain temperature are not discharged as overhead vapor. For this reason or the like, not all the feedstock is separated into high volatile components and low volatile components, and thus the non-separated material is supplied to the second stripping vessel 112 to be further separated.
The overhead vapor discharged from the first stripping vessel 111 exchanges heat with water in the condense-evaporator 120 to generate saturated water vapor, and then passes the first compression module 141, and is re-supplied to the first stripping vessel 111. In the first stripping vessel 111, this re-supplied water vapor is used to separate the feedstock material.
Meanwhile, the overhead vapor not condensed in the condense-evaporator 120 is supplied to the condenser 130, and is condensed for the last time. The condensed solution generated in the condenser 130 is separated from water based on specific gravity, and is supplied to a distillation column 180. A re-boiler 190 supplies steam to the distillation column, and steam condensate water generated in the re-boiler 190 is expanded under low pressure (flashed), and then compressed in the second compression module 142, and then supplied to the second stripping vessel 112. This steam condensate water supplied to the second stripper vessel 112 exchanges heat with the feedstock material discharged from the first stripping vessel 111, and is used for the final stripping.
That is, the condensed solution that has been condensed and separated in the condenser must be supplied to the distillation column 180 to be distilled, and the high temperature steam condensate water must be expanded and evaporated in the re-boiler 190, and then compressed in the second compression module 142 and supplied to the second stripping vessel 112. Generally, it takes several hours for a multi-stage stripping process to stabilize after the overhead vapor discharged from the first stripping vessel 111 is condensed and separated and supplied to the distillation column. In order to initially drive the first stripping vessel 111, steam is supplied from the steam supplier 160 according to the temperature required in the first stripping vessel 111, and even when the water vapor generated by the heat exchange between the overhead vapor discharged from the first stripping vessel 111 and water passes the first compression module 141 and is supplied to the first stripping vessel 111 again and used, the steam is not sufficient to operate the first stripping vessel 111, and thus steam must keep being supplied from the steam supplier 160.
For this reason, due to the excessive amount of steam that needs to be supplied from outside until the second stripping vessel 112 operates to supply the overhead vapor of the second stripping vessel 112 to the first stripping vessel 111, it costs a lot of money. Further, since the temperature condition required in the second stripping vessel 111 is higher than the temperature required in the first stripping vessel 111, there occurs a problem where the first compression module 141 and the second compression module 142 must be driven separately.
Various systems are known in the art. However, their structure and means of operation are substantially different from the present disclosure. At least one embodiment of this invention is presented in the drawings below and will be described in more detail herein.